When you use migrations, you have to manually create your data model from the .momd bundles. So for your managedObjectModel accessor method that gets created in your application delegate you need to change it slightly from what gets implemented by default:
- (NSManagedObjectModel *)managedObjectModel {
if (managedObjectModel != nil) {
return managedObjectModel;
}
// modified method
NSString *path = [[NSBundle mainBundle] pathForResource:@"VideoInfo" ofType:@"momd"];
NSURL *momURL = [NSURL fileURLWithPath:path];
managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:momURL];
return managedObjectModel;
}
There's a great explanation of this here.